Inverse Opal Photonic Crystals for Real-Time Identifiable Labels via Ultraviolet and Near-Infrared Light

Abstract

In this work, we developed inverse opal photonic crystals (IOPCs) for real-time identifiable labels by tuning the structure color and chemical color under ultraviolet (UV) light and near-infrared (NIR) light. We prepared IOPCs by etching a silica photonic crystal template in thermosensitive hydrogel added to 2,2-diphenyl-2H-naphtho [1,2-b] pyran-6-carbaldehyde (NP). In this way, the transparent hydrogel turned red under UV light due to the photochromic naphthopyran. Meanwhile, the green structure color of IOPCs was superimposed with the red chemical color of the hydrogel, so that IOPCs with naphthopyran (IOPCs/ NP) appeared yellow. When irradiated by NIR light, the structure color of IOPCs turned blue from green due to the volume contraction of the thermosensitive hydrogel. When irradiated by UV and NIR light simultaneously, the blue structure color of IOPCs was superimposed with the red chemical color of the hydrogel, and the IOPCs/NP would finally appear purple. Thus, we realized the real-time controllable IOPCs by two light sources. Based on this, we designed a series of identifiable labels with multiple colors under UV and NIR light, which expanded the application of information anticounterfeiting and identification.

Dual-Stimuli-Responsive and Anti-Freezing Conductive Ionic Hydrogels for Smart Wearable Devices and Optical Display Devices

“…In addition to this, UV/strain dual-responsive hydrogels can also monitor UV intensity outdoors. The hydrogel prepared in this study can be applied to different fields due to its remarkable properties, − such as flexible wearable devices, copy paper, , and dual-response interactive devices. , …”

Multi-stimuli responsive photonic hydrogel based on a novel photonic crystal template containing gold nanorods

“…[1][2][3] Therefore, a series of PC materials with vivid structural colors have been fabricated, which have significant application value in sensors, [4][5][6] drug delivery, [7][8][9] actuators, [10][11][12] printing [13][14][15] and other fields. [16][17][18] A hydrogel is a stimulus-responsive material due to its elastic network that can shrink and swell, so it is usually combined with PC to fabricate stimulus-responsive photonic hydrogels, which realize a visual conversion to optical signals by changing structural colors in response to external stimuli, such as light, 19,20 organic compounds and solvents, [21][22][23][24] metal ions, 25,26 temperature, [27][28][29] and pH. [30][31][32] For example, Zhao et al 33 combined a polymeric hydrogel with an SiO 2 inverse opal structure to prepare an inverse opal hydrogel (IOH) sensor which can respond to pH, temperature and ultraviolet light.…”

Photonic Crystal Films Based on Polymer Particles with a Core/Shell Structure Responding to Ethanol

“…Photonic crystals (PCs) are a class of materials that are promising both for studying new fundamental phenomena in quantum and nonlinear optics and for creating hierarchical materials with new physical, physicochemical, or biological properties. − The fundamental property of PCs is a spatially periodic change of its permittivity with a period comparable to the light wavelength. − Since the reflection wavelength of a polymer film based on PCs can be easily varied by changing the diameter of monodisperse polymer particles, − it is possible to create optical sensor materials based on polymeric PCs. Also, the reflection wavelength of the PC-based film can be modulated by changing the lattice spacing due to external influences, such as temperature, pressure, and the presence of volatile organic compounds. − PCs with tunable optical properties have great potential for a wide range of applications such as strain sensors or smart labels. − …”